The overall objective of the proposed research is to contribute to an understanding of the kinetics of spike generation, when squid giant axons are stimulated with AC sinusoidal current and with white noise. Preliminary results have already revealed results not expected from our currently best formalism, the Hodgkin-Huxley equation. I hope to follow up these leads. Theoreticians have often expressed the wish that experimental data be obtained to test their modeling in the area of threshold and excitation. It is hoped that these data for squid axon membrane will constitute a model for the more complicated situation of a network, receiving a number, instead of just one single input. When sinusoidal stimulation is utilized, I hope to be able to determine if the criterion for the AC excitation threshold is a critical constant voltage level or a constant quantity level or whether it is one or the other, depending upon the frequency of the AC stimulation used. This may lead to insights regarding the equivalent electrical circuit of the membrane and the dynamics of spike generation. Phase locking and encoding will also be studied. BIBLIOGRAPHIC REFERENCE: Guttman, R. and Feldman, . White Noise Measurement of Squid Axon Membrane Impedance, Biochem. Biophys. Res. Commun. 67:427, 1975.